How Does Mpox Spread?

To mitigate mpox (formerly known as monkeypox), health experts have long recommended avoiding close contact with infected people and contaminated objects. But amid an unusual global outbreak of the disease, scientists are investigating whether the rare disease is spreading in other ways.

But the current cases don’t all look like traditional mpox, and scientists are investigating the unusual ways in which the virus may transmit.

Experts assure a pandemic-weary world that the mpox virus does not transmit as easily as the highly contagious COVID-19 virus.

While COVID-19 can linger in the air in tiny aerosolized particles that can travel some distance, mpox is mostly spread through direct contact with open wounds, sores, and scabs from the infection. It can also spread via respiratory droplets, which don’t travel far.

In this outbreak, the modes of transmission may be more complex. In many of the recent cases, the symptoms present differently than in traditional mpox. This leaves health experts to question whether it’s possible that someone can become infected even without direct exposure to an infected person or object. According to the World Health Organization (WHO), it might also spread via “short-range aerosols.”

“It’s still too soon for us to be certain that we know all of the ways that monkeypox can spread. What we do know is that most infections to date have been acquired through direct contact with people who are infected,” W. Ian Lipkin, MD, a professor of epidemiology and director at the Center for Infection and Immunity at the Columbia University Mailman School of Public Health, told Verywell in an email.

Research on mpox transmission will be important to inform recommendations for minimizing exposure, such as using personal protective equipment, enhancing ventilation, and directing isolation measures.

Mpox Usually Spreads Through Close Contact

The primary way the virus spreads, according to the CDC, is through intimate skin contact, such as during sex, kissing, cuddling, or touching parts of the body with mpox sores. The virus is passed to healthy people through bodily fluids, lesions, and respiratory droplets of infected people or animals.

Unlike the COVID-19 virus, mpox can linger for a long time outside the body. This means it can infect people through exposure to contaminated items. This includes clothing, bedding, electronics, and sex toys.

Items can be disinfected with household cleaners that are labeled by the Environmental Protection Agency for their ability to neutralize pathogens, including the mpox virus.

In a study of four early mpox cases in Europe, researchers found evidence of the virus in the semen of three of the patients. It is likely that someone could contract the virus if they’re exposed to infected semen, though mpox is not considered a sexually transmitted infection.

“This is not equivalent to defining semen exposure as essential to transmission,” Lipkin said. “There is risk in any contact with someone who is infected irrespective of whether that contact is skin-to-skin or occurs through an object like a sex toy.”

It’s not likely that you’ll be exposed to mpox in public, like when sitting next to someone on a train or while waiting in a doctor’s office.

“The number of people who are infected is still low. Thus, the chances of becoming infected in a public setting are also low. Nonetheless, it’s prudent to minimize physical contact with people you don’t know,” he said.

Beware of Animal-to-Human Transmission

Mpox was first discovered in research monkeys in 1958. Despite the name, several different mammals, including rodents and non-human primates can carry the virus. In the U.S., the first case in a 2003 mpox outbreak came from a prairie dog bite.

Scientists don’t yet know which animal species the virus depends on for survival, though rodents are the most likely candidate. The CDC said to treat all animals with caution and to practice good hygiene.

Humans can be exposed to the bite or scratch from an infected animal, eating or handling wild game, or using products made from an infected animal, the CDC said.

There are no known cases of a human passing the virus to animals, though it may be possible. Disposing of waste like bandages and avoiding contact with pets when sick with mpox could minimize transmission both to other humans and pets.

Can Masks Stop the Spread of Mpox?

In June, the CDC recommended wearing a mask. But the agency soon removed the guidance from its website to avoid causing confusion, according to the New York Times. People who are infected with mpox and household contacts are still recommended to wear a surgical mask.

The CDC said that while it’s possible that the virus can be spread through respiratory droplets, these will “drop out of the air quickly” and aren’t likely to cause infections.

However, an August paper published out of Spain suggests skin-to-skin contact during sex is the primary mode of mpox transmission, and is much more likely than any sort of airborne transmission.

Lipkin said he would encourage people to wear a mask if they feel more comfortable with it.

Lingering Questions

Researchers are grappling with several questions about the current outbreak.

For instance, there is no evidence that mpox can be transmitted asymptomatically. But in some countries, new cases are appearing even among people who have not had contact with sick individuals, “suggesting that chains of transmission are being missed through undetected circulation of the virus,” the WHO said.

Researchers are still trying to understand how common asymptomatic infection may be, and whether it’s possible for people who are infected but don’t have symptoms can pass the virus on to others.

At a WHO conference, some scientists questioned how long mpox has been circulating, undetected, in countries including the U.S. before the first cases were diagnosed. Plus, many of the current cases outside of Africa are relatively mild, and scientists aren’t sure why.

Researchers are also looking to learn more about the significance of transmission through respiratory droplets as well as through vaginal fluids and semen during sex.

“It’s important to understand that there is still much that we don’t know and that answers may change as we learn more and the virus spreads,” Lipkin said.